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    TECLINE V2 ICE Mono Semi-Tech First Stage Regulator



Our Advice: Start your recreational diving with a regulator and standard hose lengths that can be easily transitioned to technical diving to minimise your equipment spend over time.

Diving regulators are designed to take the high pressure gas from our tanks and reduce it down to a suitable flow rate and pressure for the diver to be able to inhale. They are comprised of a first stage regulator, which is fitted directly onto the tank and a second stage regulator, which is connected to the first stage with a low pressure hose and used as the diver’s mouthpiece. 

Key points when buying regulators are durability, weight, flow rate, ease of servicing, and availability of service kits.  


There are four types of first stage regulators: unbalanced piston, balanced piston, unbalanced diaphragm, balanced diaphragm. The different types reflect the evolution of the technology. 

The balanced diaphragm first stage regulator is the current peak of development in regulator technology. They are reliable, easy to service, and provide consistent air flow at all tank pressures. Unbalanced regulators and piston regulators are obsolete and rarely used.  

A first stage regulator governs the Intermediate Pressure (IP) to the second stage demand valve by reducing the 232-300bar | 3365-4351psi tank pressure down to a much safer level. This IP is typically in the range of 8-10bar | 116-145psi and is adjusted internally via shims or a screw. If the IP range climbs above 13bar | 188psi, it will result in a freeflowing second stage regulator and will need adjustment or servicing.  

How does a first stage regulator work? 

  1. When the pressure in the intermediate pressure chamber drops below the sum of main spring pressure plus ambient water pressure (external pressure), the excess external pressure pushes the first stage diaphragm inward; 
  2. The diaphragm opens the poppet valve, connecting the intermediate and high pressure chambers until the increasing pressure in the intermediate pressure chamber equalises external pressure; 
  3. When equalised, the valve spring returns the poppet assembly and diaphragm to the closed position. 

Most modern regulators on the market offer a downstream design for gas flow. This means that the valve which opens to supply gas to the first stage moves in the same direction as the gas flow itself. If the first stage regulator fails, it will fail open, resulting in a freeflowing second stage but still allowing the diver to access the gas. In the upstream design, the gas flow is opposite to the valve direction. If an upstream regulator valve fails, the gas supply will be cut off from the diver, which could be immediately life threatening. 

Yoke vs DIN

The first stage tank fittings can come in either Yoke or DIN type. The yoke type is an A-clamp, which has a large rear mounted hand screw to secure the A-clamp onto the tank valve O-ring seating surface. The O-ring is not fully captured and as such, O-ring ruptures or extrusions can occur, including when the yoke is knocked and loosened during a dive. Yoke style regulators are not recommended for this reason.  

DIN type fittings are considerably more secure and utilize a fully captured O-ring within the regulator DIN fitting itself. This O-ring can be inspected by the diver very easily before fitting the regulator onto the tank. When the DIN screw is fastened, there is very little chance of rupture or extrusion of the O-ring. During the dive, the DIN fitting is held in place by the force the tank air pressure exerts on it, and subsequently, it is extremely difficult to knock a DIN fitting loose during a dive.  

DIN fittings are the preferred choice of all technical divers and are a perfect choice for recreational divers alike. Divers seldom have to replace a DIN O-ring between annual services.  If yoke tanks are the only type available when travelling, then a DIN to Yoke adapter can be easily purchased for a few dollars. However, it is considerably more difficult to convert the other way around with Yoke to DIN. So again, DIN regulators should be considered as the ideal choice. 

Sealed vs unsealed  

An unsealed diaphragm regulator only exposes the diaphragm and the main spring mechanism to the outer elements. Many diaphragm regulators are often sealed with a secondary seal known as an Environmental Seal which ensures that only the outer secondary diaphragm is exposed to the elements.

M25 and M26

In Europe, from 2008, tank valves and regulators used with oxygen content above 23% were required to use 26mm | 1.02in fittings (M26) to distinguish them from the 25mm | 0.98in fittings used for normal air equipment.  The intention (poorly conceived) is to make the equipment used with different gas types incompatible. Yes you can get adapters, and they are a good idea to carry.   


Some manufactures produce lightweight regulators made from titanium which are very good for travel. Unfortunately titanium may ignite when exposed to high oxygen concentrations and so is not suitable for use with nitrox mixes above 40%. 


How does a second stage regulator work? Second stage regulators are a demand valve: a diver demands gas by breathing in. 

  1. The diver inhales lowering the air pressure inside the second stage chamber to below the ambient water pressure. 
  2. Higher external water pressure presses the diaphragm towards the diver, working the demand lever. 
  3. The demand lever opens the second stage valve, allowing air to flow into the second stage from the first stage until the air pressure inside the second stage chamber equals the ambient water pressure. 
  4. When the second stage chamber is equalised to ambient water pressure, spring tension returns the demand lever and diaphragm to neutral, closing the second stage valve. 

When exhaling, the over pressure in the second stage chamber is expelled through a simple one way valve. A good design feature is an extended exhaust, so that exhaled air is directed somewhat to the sides, away from your face. 

The amount of force required to open the second stage valve to allow the gas to flow is referred to as the Cracking Pressure. The cracking pressure is adjustable but is typically between 2.5-4cm | 1-1.5in of water. The lower the number, the easier the second stage will deliver gas to the diver, but equally, the easier it will free flow. Setting the correct cracking pressure is a very delicate adjustment between an easy to breathe and a very hard to breathe regulator and requires specialised tools including a manometer.  

Some second stage regulators feature an adjustable viva control lever and/or a diver adjustable breathing effort screw. These two devices allow a second stage to be highly tuned, yet still be able to be adjusted for more or less sensitivity by the diver, primarily when they are not being used. This helps to prevent a free flow but still obtain sufficient gas even when fully tuned down (although harder to breathe).  


Standard hose lengths 

Recreational Twinset         Stage/Deo or
High Pressure
15cm | 6in (0.5ft) SPG SPG
61cm | 24in (2ft) SPG SPG
Low Pressure
56cm | 22in (1.8ft) BCD/Wing Inflator
Drysuit Inflator
Wing Inflator
Drysuit Inflator
Wing Inflator
Drysuit Inflator
Wing Inflator
Drysuit Inflator
61cm | 24in (2ft) Primary Regulator Secondary
104cm | 41in (3.4ft) Secondary
210cm | 82in (7ft)  Primary 

 You will see from the above table that there is a lot of overlap in hose lengths.  With a little attention to detail the regulator and hoses you buy for a first regulator set can be transitioned for use on a twinset and side-rigged.  

All fittings should be stainless steel. 

Rubber vs braided nylon

Are braided nylon (e.g. Miflex) hoses better than rubber hoses?  Double braided nylon hose is tough, flexible, and lightweight for travel. The extra flexibility is great for CCR applications where hoses must be threaded through different parts of the unit. Unfortunately there are a number of disadvantages: 

  • Soft and flexible enough to kink, either in equipment setup or when passing off a long-hose if a loop is pulled through (a critical failure in an emergency situation); 
  • Positive buoyancy underwater due to light weight causes the long hose to float above your head; 
  • Abrasion of the back of your neck, drysuit, and other equipment; 
  • Too flexible to easily re-stow regulators on stage cylinders in-water after use; 
  • Too much flexibility causes SPGs to flop about;  
  • Threads snag and become like toothbrushes when dragged over harsh surfaces (e.g. through a cave);  
  • Has not proven to have a practical lifespan greater than rubber; and 
  • Comparatively expensive. 

Overall there are comparatively few applications (only wing/BCD inflator, secondary recreational regulator, CCR) where the more expensive braided nylon is a better choice than rubber.  

Hose protectors

Hose protectors on the ends of the hoses near the first and/or second stage provide no practical advantage other than marketing for the brand of your regulator.  Hoses fail due to gas pressure, age, and damage.  They do not fail due to ordinary movement in the hose next to the fittings.

Hose fittings cause a number of unnecessary problems: 

  • Interfere with routing and streamlining, 
  • Prevent visual inspection of hoses, and 
  • Hold water against the stainless steel fittings causing corrosion. 

For these reasons, never install hose fittings on purpose, and if your hoses came with hose fittings the first setup/maintenance task is to cut them off (do not pull them off putting unnecessary pressure on the hose fitting).  


Submersible Pressure Gauges (SPG) are used to tell the contents of the diver’s tanks. Mechanical SPGs use Bourdon tubes sensitive to very small pressure changes. The tubes contain oil and end with a diaphragm that the air pressure pushes against. Digital models use transducers that convert air pressure into electrical signals that send the information to pressure readings on the small screen. 

SPGs are most accurate in the central range of the gauge graduations and divers should avoid breathing their tanks below 50 bar | 725 psi because the low pressure reading may be inaccurate by as much as 40%.  

Most SPGs, regardless of their branding, are manufactured by Termo Industria in Italy. Your SPG should have a metal body with a glass face. Standard sizes are: 

  • Primary SPG 60mm | 2.36in diameter, and 
  • Secondary SPG (stage/deco cylinders) 50mm | 1.97in diameter. 

Plastic SPGs are cheap and nasty, and not durable enough to rely upon.

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